Joec, you are referring to a tillering stick. Much different than a tillering tree.
A tiller tree doesn't need any plans. It can be a simple as a small piece of 2x4 mounted on the wall at eye level to set your bow on, with a rope and pulley mounted directly below, a few inches off the floor. Most people use a ruler of some sort for measuring the draw length, and an in-line scale to see the weight you are drawing.
It's easy, no plans necessary.